The above graph plots the number of monthly trips against months since launch for various cities across the globe. Red lines are Chinese cities, and blue lines are everywhere else. It shows growth in a country unlike anything Uber has seen elsewhere in the world. It's stratospheric.

Kalanick speaks in China. REUTERS/Kim Kyung-Hoon Kalanick doesn't think this growth is down to the sheer scale of China, however. "When you're talking about your first 1 million customers in each city, it doesn't matter how big the city is, there're more than enough left," the CEO says. "But what we find is, even among the initial customers, our growth in China has gone much faster than what we've seen elsewhere."

So what's the reason? "I believe it's because of the way Chinese people and Chinese social products allow people to interact and socialize and spread the word about things that are interesting. That's interesting because that means every new technology that comes out will spread faster in China."

Uber is taking a different tack it has elsewhere in the world. It is actively seeking out Chinese investors, and running the operation as a distinct unit. For Kalanick, this is about making Uber China into a "real Chinese company."

He explains: "We could have continued to run Uber as a part of Uber Global, but it was important for us to make it a Chinese company and get Chinese investors. Just like we have Chinese general managers operating and building the business, we should have Chinese shareholders as well."

The 38-year-old billion are says that "China is so different from the rest of the world ... to understand how different it is, [Uber China] should be a separate entity with separate management and separate headquarters. We want to make sure that Uber (China) is authentically and thoroughly Chinese, a real Chinese company ... For a company that at least started foreign, but is now becoming Chinese, the standard or the bar for being Chinese is higher than the traditional Chinese company. So we have to go above and beyond in becoming truly Chinese."

But the scale of the growth Uber is seeing makes it clear why the startup is being put off. In a document to investors leaked in early June, Kalanick wrote that "to put it frankly, China represents one of the largest untapped markets for Uber, potentially larger than the US."